This section provides background information related to the present disclosure which is not necessarily prior art.
Direct-ink writing (DIW) is an additive manufacturing technique capable of creating micro-scale and macro-scale structures with extreme precision. It works well with a variety of materials, including mixtures and composites of materials derived from multiple sources.
In some applications the feedstock material (ink) can comprise multiple constituents. For example the feedstock can consist of a mixture of different chemical or structural components. In precision manufacturing it can be important to maintain precise control over the feedstock composition. Thus where two or more feedstock constituents are mixed upstream, precise control over the mixture is needed. In some applications, the mixture may need to be tuned in real time, as the additive manufacturing process is underway. In other applications, the mixture is prepared in advance, making it desirable to test, monitor or validate the composition to determine if the resultant manufactured product is within compositional tolerances.
While the ability to monitor and control the feedstock composition can be important in manufacturing both micro-scale and macro-scale products, doing so becomes quite a bit more difficult for micro-scale structures (e.g., structures having a scale in the sub-millimeter range, such as on the order of 150 microns or smaller). There are several reasons for this. First, the physical properties of micro-scale structures can be inherently more difficult to assess than with macro-scale structures. Second, even minute changes in the material delivery system can have a big impact on the composition of the manufactured product. Third, changes I ambient temperature and pressure conditions can effect significant changes in the composition.